In the technical field of the internal combustion engine, there has heretofore been well known a system for controlling variably the operation timing for at least one of an intake valve and an exhaust valve of the engine in dependence on the operation state thereof with a view to enhancing efficiency of intake and discharge operations of the engine cylinders. In most internal combustion engines, the engine cylinder intake and exhaust valves are opened and closed by cams which are driven to rotate by camshafts powered by crankshaft of an engine in a pure mechanical manner. As the engine performance is highly affected by the operation parameters of its intake and exhaust valves regarding to their opening and closing, there are already many valve control mechanisms been developed for fabricating a better engine
In many such technically advanced engines current available on the market, it is common to use a computer to control and vary the open/close timing of the intake/exhaust valves for allowing the same to match the performance of the engine at different loads and speeds by that the output and fuel economy of the engine can be improved. Such variable valve control system is often be addressed as the intelligent valve control system, and moreover, when the valves in such intelligent valve control system are opened and closed and held open or closed by means of electromagnets, the system can be addressed as the electrical valve control system.
The aforesaid intelligent valve control system has many advantages as it is designed to control the opening duration of each and every intake valves and exhaust valves independently and respectively, by that it can be programmed by artificial intelligence for varying the valve opening duration to match an engine's rotational speed and thus improving the power output as well as the fuel efficiency of the engine. When an intelligent valve control system is applied in an engine, the optimum timing regarding to the opening and closing of each intake/exhaust valves can be obtained for allowing optimun engine performance at different loads and speeds. Operationally, it can prompt the intake valves and the exhaust valves to be opened completely at the instant when the engine is being ignited regardless the customary timing of the intake/exhaust valves, by that as the air in the cylinder of the engine will not be compressed, not only it can facilitate the RPM of the engine to be raised rapidly and thus the engine can be started without causing the starter motor to exhaust too much electricity, but also it can prolong the lifespan of the starter motor especially when the vehicle using the engine is in stop-and-go traffic constantly. Moreover, when the intelligent valve control system is applied in a multi-cylinder engine, it can command some of the cylinders to be deactivated when they are not needed according to the operation condition of the engine, by that the intake valves and exhaust valves of those deactivated cylinders are closed completely regardless their customary timing so as to prohibit air from flowing in and out of those deactivated cylinders and thus enhance the engine efficiency. In addition, when it is applied in a multi-cam engine, i.e. an engine that have more than two intake valves in each cylinder, and the engine is operating in a low load/load RPM condition, the intelligent valve control system will enable only one intake valve for each cylinder in the engine while disabling the others by directing those other valves to be closed completely, so that the fuel consumption of the engine can be reduced as the intake efficiency for the engine in the low load/load RPM condition is enhanced. As the electrical valve control system use solenoid valves or electric motors to control the opening and closing of the intake/exhaust valves, the open/close timing of the intake/exhaust valves are easier to be varied comparing with those conventional mechanical-driven intake/exhaust valves which is suitable to be applied in various engines for optimizing the performance of the same.
There are already many intelligent electrical valve control system currently available. One of which is an actuation system using solenoid valves for valve control disclosed in U.S. Pat. No. 4,455,543, entitled “Electromagnetically operating actuator”. The aforesaid actuation system is characterized in a double-acting spring module configured therein as it is composed of two springs in a manner that when one of the two springs is being pulled, the other is being compressed, and vice versa. Since it is achievable to obtain the optimal resonant effect in the mass-spring system formed by the engagement of the double-acting spring module and the valves to be controlled, not only the response speed can be enhanced, but also the energy loss is decreased. However, there are still some problems which may be encountered with this electromagnetic methodology of using solenoid valves for valve control. For instance, as the solenoid valve uses magnet to attract its corresponding valves while resisting the resilence of the spring module, not only the resulting mechanical response is slower, but also it will consume more electricity than electric motor, so that it has poor feasibility.
Another such electrical valve actuation mechanism, which use an electric motor for valve control, is disclosed in U.S. Pat. No. 6,755,166, entitled “Electromechanical valve drive incorporating a nonlinear mechanical transformer”. The aforesaid mechanism not only has the benefit of the foregoing double-acting spring module, but also is able to control the valves to move in a non-linear trajectory by the use of a cam mechanism and thus can drive the valves to move as fast as possible without too much variation in acceleration. Thereby, the valves can be opened or closed to their maximum rapidly without bumping on the valve seats and thus causing loud noise, and therefore can maintain the maximum opening or closing for a comparatively longer duration so as to increase the total air flux per unit time that is flowing through the intake/exhaust valves. In addition, as the aforesaid mechanism is able to enable a rotation movement by the cooperation of the reciprocating electric motor and the oscillating double-acting spring module, the valves can be driven to move much faster while consuming less energy. As the reciprocating electric motor is different from the conventional rotary electric motor in that: the magnet filed in the reciprocating electric motor is not necessary to be distributed equiangularly, and also the reciprocating electric motor is not necessary to be shaped as a cylinder as it can be shaped like a semicircular cylinder or a cuboid whichever can be easier disposed in the narrow space available on the cylinder head of the engine.
Nevertheless, the foregoing conventional mechanisms still has the following disadvantages: (1) As the nonlinear mechanical transformer used in the cam mechanism for causing the valve to move in a nonlinear trajectory will exert a single-directional sidewise push force on the valve levers, the valve levers can be skewed or can be overly rubbed on a portion thereof; (2) As the valves are one-stage valves that being driven by a double-acting spring module, there will be two springs working on opposite directions that are engaged with a same valve lever simultaneously and therefore, the valves being driven to close can not tightly fit on the valve seats since the force propelling the valve to raise is larger than the force dragging the valve to fit on the valve seat.